Conversion of hydrocarbons containing the nucleus of 1, 2, 3, 4-tetrahydronaphthalene to hydrocarbons containing the nucleus of indene



United States Patent CONVERSION OF HYDROCARBONS CONTAINING THE NUCLEUS OF 1,2,3,4-TETRAHYDRONAPH- THALENE TO HYDROCARBONS CONTAINING THE NUCLEUS OF INDENE Ronald D. Bushick, Glen Mills, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Sept. 20, 1966, Ser. No. 580,599

11 Claims. (Cl. 260-668) ABSTRACT OF THE DISCLOSURE Hydrocarbons containing the carbon atom nucleus of 1,l-di-lower-alkyl-l,2,3,4,-tetrahydronaphthalene and dissolved in an aromatic or aliphatic solvent are converted in the presence of HFBF to hydrocarbons containing an indene nucleus. For example, 1,l,4,4,5,5,8,8-octamethyll,2,3,4,5,6,7,S-Octahydroanthracene is converted to l-isopropyl-3,3-dimethylindene. Although the product always contains an indene nucleus, the specific product depends upon the type of solvent employed.

This invention relates to the rearrangement of certain types of polycyclic hydrocarbons containing a 1,2,3,4 tetrahydronaphthalene nucleus to polycyclic hydrocarbons containing an indene nucleus. For example, 1,1,4,4,5,5,8, 8-octamethyl-1,2,3,4,5,6,7,8-octahydroanthracene (herein OMOHA) and l,1,4,4-tetramethyl-l,2,3,4,5,6,7,8-octahydroanthracene (herein TMOHA) are converted to- 1- isopropyl-3,3-dimethylindene (herein 1) and l-isopropyl- 3,3,5,5,8,8 hexamethyl 5,6,7,8 tetrahydrobenzindene (herein II) respectively.

In Canadian Journal of Chemistry, vol. 39, p. 870, 1961, Barclay discloses that OMOHA rearranges in the presence of a solvent and aluminum chloride. If the solvent is tetrachloroethylene or carbon disulfide the product is II whereas if the solvent is benzene the product is 1,1,4,4-tetramethyl-l,2,3,4-tetrahydronaphthalene.

I-have nOW found that in the presence of benzene and using HFBF instead of aluminum chloride product I is obtained. In addition, I have found that products I or II can be obtained through the rearrangement of TMOHA in the presence of HFBF and a specific type of solvent. If the solvent is an aromatic such as benzene the product is I whereas if the solvent is an aliphatic (preferably saturated) such as heptane the product is II. Analogous reactions take place with analogous starting materials.

3,412,166 Patented Nov. 19, 1968 "ice The starting materials in the invention are polycyclic hydrocarbons containing the carbon atom nucleus of 1,1- di-lower alkyl-1,2,3,4-tetrahydronaphthalene. T-his nucleus is the following:

where R is a lower alkyl group such as methyl, ethyl, propyl and isopropyl. R normally will not contain more than 4 carbon atoms and is preferably methyl. Examples of compounds containing this nucleus are 1,1-dimethyl 1,2,3,4-tetrahydronaphthalene, 1,l,4,4-tetramethyl, 1,2,3,4- tetrahydronaphthalene, TMOHA, and OMOHA. It Will be noted that so long as the specified nucleus is present it may have alkyl groups attached thereto and/or other rings condensed therewith, but any such rings are preferably condensed with the aryl ring of the nucleus. Normally any such alkyl substituents will contain not more than four carbon atoms and preferably are methyl. The preferred starting materials are 1,l-dimethyl-l,2,3,4-tetrahydronaphthalene, l,1-dimethyloctahydroanthracene and alkyl derivatives thereof, more preferably TMOHA and OMOHA.

The products obtained by the rearrangement of the above described starting materials according to the invention contain the indene nucleus which is:

The indene nucleus is formed by contraction of the saturated ring in the 1,1di-lower alkyl l,2,3,4-tetrahydronaphthalene nucleus of the starting material. This contraction expels a carbon atom which in combination with the two lower alkyl groups on the starting material forms a single alkyl group in the one position of the indene nucleus. For example,

The starting materials are rearranged according to the invention by contacting same with HFBF at a temperature of 10-100 C., in the presence of a solvent, and for a time suflicient to effect ring contraction as described above. The amount of HF should be at least 1 mole per mole of starting material and the amount of BF should be at least 0.1 mole per mole of starting ma- 3 4 terial. Preferably the mole ratio of HF and B F to startflushed out with nitrogen and is then evacuated. A 10 mg material 18 at least 10:1 and 05:1 respectively, more weight percent solution of the starting material in solvent perferably at least 50 :1 and 1.0:1 respectively. The HF is charged to the reactor, the solution is frozen by means should be employed 1n liquid phase. Normally the BF of Dry Ice, and the HF is then drawn in. The amount of pressure in the reaction vessel is suificient to maintain 5 starting material employed is one gram and is the same the HF in liquid phase but if not the vessel can be presin all runs. The B1 is then added, the reactor is shaken sured with nitrogen, etc. in order to achieve this result. and is then heated to the desired reaction temperature. In The reaction time required to effect ring contraction is all runs the BF pressure is sufficient to maintain essennormally l-120 minutes but preferably the reaction time tially all of the HF in liquid phase. The reactor is then is -120 minutes. Preferably the temperature is 20 held at the reaction temperature for the desired reaction 70 C. and in any event it should be above the freezing 10 time. Shaking of the reactor continues throughout the point of the solvent. entire reaction time. At the end of the reaction period the The type of solvent employed will determine the spereactor is cooled to 0., opened, and the contents cific products obtained. For example, with a polyalkylthereof quenched in ice. Two liquid layers result, an aqueoctahydroanthracene such as TMOHA and an aromatic ous acid layer and an organic layer. This two-phase syssolvent such as benzene one ring of the starting material 0 tern is neutralized with Na CO after which the organic is eliminated and the product is 1 Whereas the use of an layer is drawn off and washed several times with twice its aliphatic solvent such as heptane with the same starting Volume of Watef- The Organic layflf is then analyzed y material yields H with no ring elimination. Although other vap pha e Chr t grap y and the r sults are as Sh wn solvents can be employed, e.g., hexane, the solvent should in the Table I below. Analagous results are obtained with be inert by which is meant that it does not interfere with Other Starting materials of the y described and other the reaction. The amount of solvent employed should be reaction Conditions e specified- TABLE I Reaction Catalyst Composition oi Reaction Product Mixture, wt. percent Mole Ratios Run Starting Solvent Material Temp., Time, HF to 131% to l,2,3,4-tetra- 1,l,4,4- Starting 0. min. Starting Starting hydronaphtetramethyl- Material I II Other Material Material thalene tetralin 442525 OMOHA Benzene 3O 179:1 1.3:1 17. 7 442698 TMOHA do 50 60 245:1 2.5:]. 34.9 11.8 442699 TMOHA do 50 60 256:]. 16.6:1 40. 7 12.5 467537-3 TMOHA Heptane 50 60 13011 1.811 13. 6 25.5

sufiicient to dissolve all the starting material. Normally 59 The invention claimed is: a l-50 weight percent solution of starting material in 1. Method which comprises contacting a polycyclic solvent will be used. hydrocarbon containing the carbon atom nucleus of 1,1-

The starting materials of the invention can be made di-lower alkyl-l,2,3,4-tetrahydronaphthalene with liquid by known techniques. See, for example, JACS, vol. 62, HF and 3, Said p y y hydrocarbon being dissolved pp. 41-43, 1940, in an aromatic or aliphatic solvent therefor, said contacting being at a temperature of 10-100 C., the amount of HF being at least one mole per mole of said polycyclic hydrocarbon and the amount of BF being at least 0.1 mole per mole of said polycyclic hydrocarbon, continuing said contacting for a time sufiicient to effect contraction of the six-membered ring of said nucleus to a fivemembered ring, thereby to form a polycyclic hydrocar- The rearrangements can be carried out in any convenient manner in conventional equipment. For example, a solution of the starting material in the solvent is charged to a closed reaction vessel equipped with heating and agitation means. The reactor is then immersed in a dry 45 ice bath to freeze the starting material solution so that it will not boil when the reactor is subsequently evacuated to draw in the HR The required amount of is then bon product contaimng the carbon atom nucleus of added in the manner described after which the reactor is mdene' removed from the ice bath and the desired amount of Method according to claim 1 wherein the p BF is added. The vessel is then preferably shaken or the ture iS in the range of contents thereof otherwise agitated in order to insure effi- 3- Method according to cl 1 in said p y y Cient Contact Of the catalyst the starting y g is 3 material. After adding the B1 the reaction mass is heated tahy to and then maintained at the desired reaction tempera- Method according to Claim 1 wherein Said P y y ture for the desired reaction time. At the end of the reachydrocarbon is Y l'- tion period the vessel is opened, which eifects removal ccneof most of the BF and the remaining reaction mass is 5. Method accordin to claim 1 wherein Said S01v6!" quenched in ice water. Two liquid layers result, an aque- S ben ene.

ous acid layer and an organic layer. If desired, the acid 6. Method according to claim 1 wherein said solvent in this two-phase system can be neutralized by mixing the S hcp anesystem with Na CO The organic layer is then decanted 7. Method according to claim 1 wherein said polycyclic and is preferably washed with water several times to rehy r c rb n is 1,1,4,4,5,5,8,8-octamethyl-1,2,3, move any remaining traces of acid 01' any trac of octahydroanthracene, said solvent is benzene, said prod- Na CO The rearrangement product is then separated 5 llct s -iS pr0pyl-3,3 dimethylindene, and the latter is refrom the organic layer by conventional means such as covered from the reaction product mixture.

distillation or chromatography. Any unreacted starting 8. Method according to claim 1 wherein said polycyclic material can also be recovered by conventional means hydrocarbon is 1,1,4,4-tetramethyl-1,2,3,4,5,6,7,8-octahyand can be recycled to the reaction vessel for subsequent droanthracene, said solvent is benzene, said product is rearrangement. 1-isopropyl-3,3-dimethylindene, and the latter is recovered The following examples illustrate the invention more from the reaction product mixture. specifically. The procedure in each run is essentially the 9. Method according to claim 1 wherein said polycyclic same and is as follows: hydrocarbon is l,1,4,4-tetramethyl1,2,3,4,5,6,7,8-octahy- The reaction vessel is a small reactor equipped with droanthracene, said solvent is heptane, said product is a shaker and heating and cooling means. The reactor is l-isopropyl-3,3,5,5,8,8 hexamethyl 5,6,7,8 tetrahydro- 5 benzindene and the latter is recovered from the reaction product mixture.

10. Method according to claim 1 wherein the amount of HF is at least 10 moles per mole of said polycyclic hydrocarbon and the amount of BF is at least 0.5 mole per mole of said polycyclic hydrocarbon.

11. Method according to claim 1 wherein said polycyclic hydrocarbon is 1,l-dimethyl-1,2,3,4,5,6,7,8-octahydroanthracene or an alkyl derivative thereof.

6 References Cited UNITED STATES PATENTS 5/1967 De Young 260-668 8/1967 Bushick 260-668 

